Usage depleted overnight. All updates set during free time.

I have had the same router for at least 2 years.  NetGear WNR1000.  One laptop that is never left on  over night.  The status meter is downloaded on it and I am always aware of data usage. We have a desktop computer with all updates set overnight and it is left on most of the time.  We have never had a problem with the settings.  It has a status meter downloaded and we watch it carefully.  My husband has had an IPhone with no extra apps on it and has had it for 10 months with no problems. I have an Iphone.  If I use my  Wi-Fi, I turn it on and watch my data on my computer.  I do not leave my phone connected to Wi-Fi overnight.  There are not other devices that can connect to Wi-Fi in our home.